EQUIPMENT AND METHOD FOR THE FLOTATION AND CLASSIFICATION OF MINERAL LECHADA
Field of the Invention The invention relates to equipment and a method for the flotation of ore slurry (silt). According to the invention, from a part of the ore slurry (silt) fed into the flotation cell, the coarse and fine materials are separated within the flotation cell for separate treatments.
BACKGROUND OF THE INVENTION Conventional flotation devices include a tank for receiving slurry (slime) obtained from a shredder, cyclone separator or some other corresponding device. In general, the tank is provided with a stirrer comprising a rotor placed inside the stator, stirrer which is activated by a motor and a drive shaft to agitate the slurry (slime). The device also includes an aeration system for conducting the pressurized air within the agitator through a central duct formed within the drive shaft. Suitable reagents are also added; these coat the surface of the selected mineral particles in the slurry and render the particles water repellent, thus advantageously assisting the bubbles to bind to the selected particles. When the bubbles are blown by the rotor they rise towards the surface of the tank, they load said selected mineral particles that form a superficial foam enriched with mineral. Subsequently, the foam advances on the foam edge of the container towards a channel, after which the mineral particles suspended in the foam are recovered from the tank as a mineral concentrate. Those mineral particles that remain suspended in the slurry (silt) and are not removed as a concentrate in the flotation process are continuously discharged from the tank through a lower outlet. The slurry (silt) discharged through the lower outlet contains both relatively thick or dense particles and a large number of relatively fine particles, including slurries, such as clay minerals, which are not discharged into the
floatation. The grouts are composed of very fine particles, and in this way the total surface area is much larger than that of the coarse particles. Therefore, when the flotation reagents are added to the slurry (slime), most of them tend to be absorbed in the part of the fine particles of the particle distribution. Most flotation reagents tend to be absorbed in the slurries, which makes the selection process not selective. In this way most of the thickest valuable particles, even with an extended processing time, do not receive enough flotation reagent in order to make them water repellent. It is generally known that a flotation process can be increased, if the coarse and fine particles are treated separately. Separate sorting devices, such as hydrocyclones and hydroclassifiers, have been used to separate the feed flow from flotation in two separate streams, to be processed separately. However, the capital costs of this type of equipment are high, which makes the prior art methods expensive for all but the most valuable types of minerals. From the patent application of the United States of America No. 5,909,022, it is known a flotation equipment for the separation of minerals within the flotation cell, said cell being provided with separate outputs both in the upper parts and in the bottom of the cell, for both coarse and fine materials. In relation to said exits, there are valves arranged to control the removal of the grout material (silt). However, by using such equipment, an equally effective way to separate the coarse and fine mineral substances is not achieved as by the use of the arrangement of the present invention.
SUMMARY AND OBJECTIVES OF THE INVENTION In accordance with the present invention, a slurry stream containing both fine particles and coarse particles can be progressively separated into two separate flows in the flotation cell. One stream contains relatively thick particles, and the other stream contains finer particles. In this way, these two flows can be optimized separately for the processing of either coarse particles or fine particles, which gives the best possible efficiency and the best cost-effective ratio.
benefit for the entire separation process. Thus, it should be understood that the invention brings remarkable advantages, both practical and economic, in comparison with prior art techniques. The purpose of an arrangement according to the invention is to introduce a new method and equipment for the flotation of ore slurry (silt), where the fine and coarse ingredients are mutually separated, that is, classified, within the cell of flotation.
BRIEF DESCRIPTION OF THE DRAWINGS The equipment according to the invention is further described with reference to the accompanying drawings, in which Figure 1 is a side view illustration of an equipment according to the invention. Figure 2 is an illustration of a device according to one embodiment. Figure 3 is a third dimension view illustration of the equipment according to the invention.
Detailed Description of the Preferred Modes of the Invention The novel features characteristic of the invention are clear from the appended claims. The invention relates to a device for the flotation of mineral slurry (silt) in a flotation cell provided with a flotation mechanism comprising at least one drive shaft, a rotor and a stator, and at least one input for feeding of mineral slurry (silt), a foam feed channel system to remove foam enriched with ore, at least two discharge outlets to remove material flows with two different grain sizes from the flotation cell, in which case the cell The flotation cell is provided with classification equipment that includes means to settle the mineral slurry (slime) to be sorted, separated from the mineral slurry (silt), in a rotary motion with an essentially upward direction in the flotation cell, as well as as means for separating coarser materials from the more finely divided material. When placed in a rotary motion, the coarse material is separated from the finely divided material
due to the effect of centrifugal force. According to a preferred embodiment of the invention, the sorting equipment is placed around the drive shaft, in which case it uses the rotational force of the drive shaft of the float cell. According to one embodiment of the invention, the sorting equipment includes at least one sorting element provided with an overflow space for the finely divided material and a sorting space for separating the fine material and the coarse material. When the feed slurry (slime) is conducted to the flotation cell, part of it is separated as mineral slurry (slime) to be sorted and is conducted to the sorting equipment placed around the drive shaft, and between the space For classifying the classification element provided and the overflow space, an opening is placed to remove finely divided material from the classification space. By means of the aforementioned opening size adjustment, the flow and grain size of the finely divided material can be controlled. According to one embodiment, the classification element extends, at the bottom of the flotation cell, to the vicinity of the rotor, at a desired distance from it, and in the upper part almost as high as the height of the foam channel system. In this way the finely divided mineral substance can be removed from the flotation cell through the upper part thereof. According to one embodiment of the invention, the sorting space of the sorting element includes a spacing element that extends around the driving axis, said spacing element extending to at least part of the height of the sorting element. According to one embodiment, the separating element is rotary due to the effect of the drive axis, in order to place the mineral slurry (slimes) to be classified in rotary motion. In relation to the separating element, at least one pumping element is provided to improve the feeding of the mineral slurry (slime) to be classified within the classification space. Additionally, the sorting space is provided with at least one orientation element to guide the flow of material to be sorted away from the drive axis, which orientation element extends around the drive axis. In this way the desired mineral substance to be separated is guided to the area of
greater centrifugal force, and the separation of the thicker material is improved. According to the characteristic features of the invention, in the space placed between the separating element and the classification element, at least one circulation conduit is provided to remove the thicker material inside the flotation cell. After being discharged from the sorting equipment, the thicker material is further mixed in the circulations of the flotation cell. According to one embodiment of the invention, the separating element is provided with outlets for the removal of thicker material. This improves the removal of thicker material from the separator element through the outlets to the circulation conduit, in addition to the fact that some of the thicker material is discharged as a spill. According to the invention, the spill space of the sorting element includes at least one outlet for the finely divided material and minus one outlet in the sorting device to remove possibly floated material and air, for example to be mixed. in the rest of the concentrate. According to one embodiment of the invention, the space between the rotor of the flotation mechanism and the sorting equipment is provided with turbulent flow prevention elements, by means of which only the flow of the mineral slurry (silt) is improved. which is going to be classified within the classification team. According to the invention, in relation to the separating element, pumping means are also arranged to improve the removal of thicker material from the sorting space. According to the invention, at least one channel is placed between the discharge outlet of the finely divided material, provided on the wall of the flotation cell and the discharge outlet of the spill space. According to the invention, in the vicinity of the discharge outlet for the finely divided material, at least one valve is arranged to adjust the discharge flow of the finely divided material. According to a preferred embodiment of the invention, the diameter of the classification element is essentially equal to the diameter of the rotor of the flotation mechanism. According to the invention, the finely divided material removed from the flotation cell is further processed in the flotation for example in other flotation equipment optimized for the finely divided material, or further processed from
another way. The classified coarse material is fed to be additionally floated or otherwise treated in a specific optimized process. Because the flotation process is generally carried out in a series of several flotation cells, it is obvious that the sorting equipment according to the present invention can be installed in several successive float cells, which improves the efficiency of classification. The equipment according to the invention for the flotation of mineral slurry (silt) is illustrated in Figures 1, 2 and 3. According to the example, a cylindrical flotation cell 2 comprises of a flotation mechanism 3 that agitates the slurry of feed (slime) 4 and places it in a rotary movement due to the influence of the rotary movement of the drive shaft 6. The flotation mechanism 3 includes a rotor 5 which is installed on the drive shaft 6 placed centrally, the which extends in parallel with said shaft down towards the flotation cell, said drive shaft being driven by a motor. Around the rotor, a stator 7 is also provided. As illustrated in the drawings, the rotor 5 is located near the bottom of the flotation cell 2. Air is fed into the flotation mechanism 3 through a hollow shaft that it is positioned to rotate the rotor 5, or through a gas inlet that is positioned below the flotation mechanism. The mineral slurry (silt) 4 that is going to be supplied in the process is conducted in the flotation cell 2 through a 1 1 inlet, the inlet which is generally formed on the side wall of the flotation cell 2. The feed slurry (slime) can also be carried to the flotation cell for example through a pipe coming from the top of the cell. During flotation, the feed slurry (slime) 4 is transferred through the stator 7 to the rotor and mixed with air, after which it is returned back into the cell space and further up into the cell together with the cells. bubbles, transporting in this way and with ingredients enriched with mineral, part of the ingredients are separated towards the mineral slurry (slime) 24 that is going to be classified. Around the inner upper part of the side wall of the flotation cell 2, a foam channel system 8 extends, from which the foam 20 enriched with mineral that has been raised to the surface is removed.
According to the invention, from the mineral slurry (silt) 4 made to float in the flotation cell 2, part is separated towards the mineral slurry (slime) 24 to be classified, in which case the coarse and fine ingredients contained in the slurry (silt) 24 that is to be classified are separated by means of the classification equipment 1 installed in the flotation cell. Thereby, a flow rate 18 for the finely divided ingredients 26 is separated, which can be treated separately. According to the invention, the sorting equipment 1 comprises of a cylindrical and stationary sorting element 9 installed around the rotating drive shaft 6 of the flotation cell 2, sorting element which defines a separate sorting space 27 for separating the coarse and fine ingredients, that is, for the classification, and a spill space 17 within which the finely divided material 26 as well as the air and concentrate are withdrawn from the classification space. Advantageously, the spill space 17 is located above the sorting space 27 in the flotation cell. The classification element 9 is attached, for example, to the structures of the flotation cell 2, so that both the classification element 9, the classification space 27 and the spill space 17 are located symmetrically around the drive axis 6. The classification element 9 includes an essentially cylindrical side wall which at the lower part extends up to the vicinity of the rotor 5, at a distance B from this, and in the upper part essentially as high as the height of the system 8 of the foam channel 8. The diameter D of the classification element 9 is in proportion to the diameter of the flotation cell, and this is advantageously of the same order as the diameter of the rotor 5 of the agitator. According to the invention, the rotating force for the mineral slurry (slimes) to be classified is obtained from the drive shaft 6. In the flotation cell, the mineral slurry (slime) 24 to be classified is placed by means of the hydrostatic pressure in an essentially upward flow and with a rotary movement within the sorting element 9, in the sorting space 27. The sorting space 27 includes a cylindrical separating element 13 which is rotary due to the effect of the drive shaft 6 and extends up to part of the height of the sorting element 9, element 13 within which the coarse material 25 is separated from the finely divided material 26 due to centrifugal force and gravity. In order to make possible the rotary movement that moves upwards for the
slurry (slimes) 24 to be classified, between the rotor 5 of the flotation mechanism 3 and the classification element 9, turbulent flow prevention elements 21 have been installed, advantageously four or more in number. Consequently, starting from the rotor 5, the mineral substance advances further towards other material flows from the flotation cell that flow upwards in the cell, and the mineral slurry (slimes) 24 to be classified can flow upwards in the cell. Sorting equipment 1. The coarse ingredients are separated from fine ingredients in the sorting space 27, from where they are removed from the interior of the separating element 13 due to the effect of the centrifugal force that causes the rotary movement, mainly as a spill . Within the separating element 13, the flow of the mineral slurry (slimes) 24 to be classified is controlled by means of an orientation element 10. The orientation element 10 is designed so that within the separator element 13, the material thick continue to its edges, away from the proximity of the drive shaft 6, towards the area of a greater centrifugal force. In this way the circulation becomes optimal, and the coarse material flows to the edges as fast as possible after entering the sorting equipment 1, and at the same time it flows upwards, until it is separated as a spill from the separating element. Additionally, the coarse material is separated as the slurry (slime) to be sorted is further conveyed upward into the sorting space 27 of the sorting element 9 as the rotary motion prevails, until the finely divided material 26 is separated from it. it is in a separate spill space 17 through an outlet 16 placed in the sorting element 9. The coarse material 25 separated in the sorting is separated due to the centrifugal force, and is carried out of the sorting element for example through of each other, a circulation duct 15 provided between the separating element 13 and the classification element 9.; when it is being discharged from said conduit, the coarse slurry is further mixed in the circulations of the flotation cell 2. According to an example of the invention, the separating element 13 is attached to the driving shaft 6. The wall of the separator element 13 can also be provided with outlets 30 for guiding the coarse material further to the circulation conduit 15, as illustrated in the embodiment according to Figure 2. The upwardly moving circulation and the rotary movement of the slurry (silt) are improved by means of a
pumping element 22, such as a propeller, placed below the sorting element 9. In relation to the circulation duct 15, the separating element 13 is provided with pumping means, such as the vanes 14, vanes which, when rotated , improve the flow of the coarse material leaving the sorting space 27 of the sorting element 9 along the circulation conduit 15 towards the flotation cell. The coarse mineral material is transferred to the flotation cell to be made to float additionally, and this sticks to the bubbles that thus form the mineral foam, but part of it is removed for separate processing through an exhaust outlet. bottom discharge 12 placed in the lower part of the flotation cell. The circulation of the fine material and the size of the grain of the solid substance contained in the slurry (slimes) are adjusted by means of the modification of the diameter A of the outlet 16. The spill space 17 includes a discharge outlet 18 for the material finely divided 26, which is further guided, along the channel 29, towards the discharge outlet 28 placed on the wall of the flotation cell 2. In the vicinity of the discharge outlet 28 for the finely divided material, it is a valve 23 is connected to adjust the amount of material flowing out. The overflow space 17 also includes a discharge outlet 19 for the air and the possible concentrate which is mixed in the foam layer 20 of the flotation cell. The flow of the finely divided material 26 to be discharged through the discharge outlet 28 and the flow of the coarse material to be discharged through the lower discharge outlet 12 are additionally fed to be floated in water circulation circuits. floating separately, or to be otherwise treated in separate processes. The diameter A of the outlet 16, the diameter of the discharge outlet 19 and the distance B between the lower edge of the classification element 9 and the agitator are selected individually for each case, according to the process conditions. The invention is further described with reference to the following example.
EXAMPLE 1 The example describes a method according to the invention for the flotation of mineral slurry, in which the fine and coarse materials are separated within the flotation cell for additional individual processes. In the cell
flotation, feed material is fed, where 56.4% of the solid substance contained in it has a grain size greater than 210 μ ??, and 9.7% has a grain size less than 37 μ? t ?. Said feed material is classified by means of a sorting equipment placed inside the flotation cell, so that the fine and coarse materials are separated. Of the divided material finely obtained from the classification, 12.0% has a grain size greater than 210 μ? and 22.9% have a grain size smaller than 37 μ ??. With regard to the solid substance contained in the coarse waste that is simultaneously removed from the flotation cell, 69.3% has a grain size greater than 210 μ ??, and 5.3% has a grain size less than 37 μ ??. By means of the application of the classification according to the invention, the majority of the finely divided material is separated from the coarse material. According to the example, even 59% of the finest material is separated in the fine product, and 77.5% of the coarse material is separated in the coarse product, which illustrates the useful nature of the present invention. The invention is not restricted only to the modalities described above, since many modifications and combinations thereof are possible within the scope of the inventive idea stated in the appended claims.